Mega RAM Loss Exists In Mac OS 8

Mega RAM Loss Exists In Mac OS 8: Reprinted with update edits from 10/7 by popular demand.

Macs Only! has covered this issue since System 7.5.3 came out -- see the RAM Loss Page. The mega RAM loss occurs when Netscape is the first application to use Open Transport after booting the computer. After quitting Netscape, "About This Computer" selected under the Apple Menu reports that the Largest Unused Block (LUB) of available RAM is reduced by about the same amount as Netscape used when open. This issue was resolved on all my computers when a late beta version of Open Transport v1.1.1 and OT/PPP came out last Fall. From considerable experimentation during the weekend of 10/5-6, I can confirm that the issue is back with Mac OS 8 and Open Transport 1.2 but in a much more limited manner.

I get the mega RAM loss by following this sequence EVERY time on my PowerBase 180 (Mac OS 8, 56 MB RAM, 512K L2 cache, 1.2 G internal ATA [IDE] hard drive):

• Startup, Open OT/PPP and make a PPP connection to my ISP
• Launch Netscape Communicator 4.03 and go to a page other than the initial page
• Launch Microsoft Word 6.01 and save a file
• Quit MS Word, Disconnect OT/PPP, Quit OT/PPP, Quit Netscape
• Read "About This Computer" and the LUB plus System File RAM usage is less than the total available RAM by the amount used by Netscape when it was open.

Memory Mapper v1.4 reports no RAM fragmentation. If I just launch and quit Netscape (i.e. do not launch Word or any other program while a PPP connection is open and Netscape is open), I never get the mega RAM loss. However, many readers wrote me that they get the loss of available RAM just using Netscape--most of them use 6400's. Having Virtual Memory on or off has no effect. Having "Load only when needed" in the TCP/IP control panel checked or not checked has no effect. But curiously sometimes closing and re-opening the "About This Computer" window restores the lost memory. Furthermore, I can not cause this problem on my 7100, 8500, 3400 or Quadra 605. The problem, which I first noticed on my 7100 last year, is now limited to just my PowerBase 180 and just under the circumstances noted. The workarounds noted on Macs Only!'s RAM Loss Page still work.

Readers have reported other memory leaks with Mac OS 8, including watching the system file size (as reported by "About This Computer") grow while doing absolutely nothing. I was unable to confirm any memory leak other than that associated with the use of Open Transport noted here. That doesn't mean that they don't happen. Please e-mail me with a description of any repeatable memory leak in Mac OS 8.

Finally, this problem is associated with Open Transport v1.2, new with Mac OS 8. After I identified it in OT v1.1 and worked with OT tech Rich Kubota on the problem, it appeared to be fixed in OT 1.1.1 and 1.1.2, the versions that preceeded 1.2. Unfortunately, some readers wrote me that the problem will carry over into OT v1.3 that will ship with Mac OS 8.1 in late December.